opengl之triangel

  记录下代码

  https://bitbucket.org/rndblnch/opengl-programmable/src/tip/10-gl3.2core.py?fileviewer=file-view-default

  部分代码借用了上述链接

shader.py

# coding: utf-8
from OpenGL.GL import *

import sys
##############################################################################
# Shader
##############################################################################
# Checks for GL posted errors after appropriate calls

shader=None
def printOpenGLError():
    err = glGetError()
    if (err != GL_NO_ERROR):
        print('GLERROR: ', gluErrorString(err))
        #sys.exit()

class Shader(object):

    def initShader(self, vertex_shader_source, fragment_shader_source):
        # create program
        self.program=glCreateProgram()
        print('create program')
        printOpenGLError()

        # vertex shader
        print('compile vertex shader...')
        self.vs = glCreateShader(GL_VERTEX_SHADER)
        glShaderSource(self.vs, [vertex_shader_source])
        glCompileShader(self.vs)
        glAttachShader(self.program, self.vs)
        printOpenGLError()

        # fragment shader
        print('compile fragment shader...')
        self.fs = glCreateShader(GL_FRAGMENT_SHADER)
        glShaderSource(self.fs, [fragment_shader_source])
        glCompileShader(self.fs)
        glAttachShader(self.program, self.fs)
        printOpenGLError()

        print('link...')
        glLinkProgram(self.program)
        printOpenGLError()

    def begin(self):
        if glUseProgram(self.program):
            printOpenGLError()

    def end(self):
        glUseProgram(0)

三角形的坐标设定,shader 代码 。主要了解到ctypes库。pyopengl库中接口的参数传递，数据类型有此库帮助更加易用。

起初一直是黑色屏幕，没有显示出三角形。加入glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)此句清除framebuffer的则可以正常输出了

# coding: utf-8
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
import sys
from ctypes import sizeof, c_float, c_void_p, c_uint, string_at

from shader import *
#https://bitbucket.org/rndblnch/opengl-programmable/src/tip/10-gl3.2core.py?fileviewer=file-view-default

     
myvertices = [
    -0.5, -0.7, 0.0,
     0.5, -0.5, 0.0,
     0.0,  0.5, 0.0
    ]
def mydraw():

    # clear
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)

    # view
    #glMatrixMode(GL_MODELVIEW)
    #glLoadIdentity()
    
    buffers = glGenBuffers(1)
    float_size = sizeof(c_float)
    vertex_offset    = c_void_p(0 * float_size)
    glBindBuffer(GL_ARRAY_BUFFER, buffers)
    glBufferData(GL_ARRAY_BUFFER, 
            len(myvertices)*4,  # byte size
            (ctypes.c_float*len(myvertices))(*myvertices), 
            GL_STATIC_DRAW)
    
    
    
    glEnableClientState(GL_VERTEX_ARRAY)
    glVertexAttribPointer(0,3,GL_FLOAT, False, 3 * float_size, vertex_offset)
    glEnableVertexAttribArray(0) 
    global shader
    if shader==None:
            shader=Shader()
            shader.initShader('''
   
    layout (location = 0) in vec3 aPos;
    void main()
    {
        gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);
       
    }
            ''',
            '''
    out vec4 FragColor;
    void main()
    {
        FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);
    }
            ''')
    
    shader.begin()
    glDrawArrays(GL_TRIANGLES, 0, 3)
    #glFlush()
    shader.end()
    glDisableVertexAttribArray(0)

##############################################################################
def disp_func():
    #draw()
    mydraw()
    glutSwapBuffers()

if __name__=="__main__":
    glutInit(sys.argv)
    glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH)
    glutInitWindowSize(256, 256)
    glutCreateWindow(b"vbo")
    glutDisplayFunc(disp_func)
    glutIdleFunc(disp_func)
    #glutReshapeFunc(reshape_func)

    #initialize()

    glutMainLoop()